In applicant's experience, on conventional rotary rigs, helpers, otherwise known as roughnecks, handle the lower end of the pipe when they are tripping it in or out of the hole. As used herein, the terms pipe and tubular are used interchangeably. The roughnecks also use large wrenches commonly referred to as tongs to screw or unscrew, that is make up or break out pipe. Applicant is aware that there are some other tongs that are so called power tongs, torque wrenches, or iron roughnecks which replace the conventional tongs. The use of prior art conventional tongs is illustrated in FIG. 1a. Other tongs are described in the following prior art descriptions.
In the prior art applicant is aware of U.S. Pat. No. 6,082,225 which issued Feb. 17, 1997 to Richardson for a Power Tong Wrench. Richardson describes a power tong wrench having an open slot to accommodate a range of pipe diameters capable of making and breaking pipe threads and spinning in or out the threads and in which hydraulic power is supplied with a pump disposed within a rotary assembly. The pump is powered through a non-mechanical coupling, taught to be a motor disposed outside the rotary assembly.
In the present invention the rotary hydraulic and electrical systems are powered at all times and in all rotary positions via a serpentine such as a serpentine belt drive, unlike in the Richardson patent in which they are powered only in the home position. In the present invention the pipe can thus be gripped and ungripped repeatedly in any rotary position with no dependence on stored energy and the tong according to the present invention may be more compact because of reduced hydraulic accumulator requirements for energy storage wherein hydraulic accumulators are used for energy storage only to enhance gripping speed.
Applicant is also aware of U.S. Pat. No. 5,167,173 which issued Dec. 1, 1992 to Pietras for a Tong. Pietras describes that tongs are used in the drilling industry for gripping and rotating pipes, Pietras stating that generally pipes are gripped between one or more passive jaws and one or more active jaws which are urged against the pipe. He states that normally the radial position of the jaws is fixed and consequently these jaws and/or their jaw holders must be changed to accommodate pipes of different diameters.
Applicant is also aware of U.S. Pat. No. 6,776,070 which issued Aug. 17, 2004 to Mason et al. for an Iron Roughneck. Mason et al. describes an iron roughneck as including a pair of upper jaws carrying pipe gripping dies for gripping tool joints where the jaws have recesses formed on each side of the pipe gripping dies to receive spinning rollers. By positioning the spinning rollers in the upper jaws at the same level as the pipe gripping dies the spinning rollers are able to engage the pipe closer to the lower jaws and thus can act on the tool joint rather than on the pipe stem. Mason et al. describe that in running a string of drill pipe or other pipe into or out of a well, a combination torque wrench and spinning wrench are often used, referred to as “iron roughnecks”. These devices combine torque and spinning wrenches as for example described in U.S. Pat. Nos. 4,023,449, 4,348,920, and 4,765,401, to Boyadjieff.
In the prior art iron roughnecks, spinning wrenches and torque wrenches are commonly mounted together on a single carriage but are, nevertheless, separate machines with the exception of the Iron Roughnecks of Mason which combines the spinner wrench rollers and torque jaws in a common holder, although they nevertheless, still work independently of each other. When breaking-out, or loosening, connections between two joints of drill pipe, the upper jaw of the torque wrench is used to clamp onto the end portion of an upper joint of pipe, and the lower jaw of the torque wrench clamps onto the end portion of the lower joint of pipe.
Drill pipe manufacturers add threaded components, called “tool joints”, to each end of a joint of drill pipe. They add the threaded tool joints because the metal wall of drill pipe is not thick enough for threads to be cut into them. The tool joints are welded over the end portions of the drill pipe and give the pipe a characteristic bulge at each end. One tool joint, having female, or inside threads, is called a “box”. The tool joint on the other end has male, or outside threads, and is called the “pin”. Disconnection of the pin from the box requires both a high-torque and low angular displacement ‘break’ action to disengage the contact shoulders and a low-torque high-angular displacement ‘spin’ action to screw out the threads. Connection of the pin and box require the reverse sequence. In the make/break action torque is high (10,000-100,000 ft-lb), having a small (30-60 degrees) angular displacement. In the spin action torque is low (1,000-3,000 ft-lb), having a large (3-5 revolutions) angular displacement.
After clamping onto the tool joints, the upper and lower jaws are turned relative to each other to break the connection between the upper and lower tool joints. The upper jaw is then released while the lower jaw (also referred to as a back-up jaw) remains clamped onto the lower tool joint. A spinning wrench, which is commonly separate from the torque wrench and mounted higher up on the carriage, engages the stem of the upper joint of drill pipe and spins the upper joint of drill pipe until it is disconnected from the lower joint. When making up (connecting) two joints of pipe the lower jaw grips the lower tool joint, the upper pipe is brought into position, the spinning wrench (or in some cases a top drive) engages the upper joint and spins it in. The torque wrench upper jaws clamp the pipe and tightens the connection.
Applicant is further aware of United States Published Patent Application entitled Power Tong, which was published Apr. 5, 2007 under Publication No. US 2007/0074606 for the application of Halse. Halse discloses a power tong which includes a drive ring and at least one clamping device with the clamping devices arranged to grip a pipe string. A driving mechanism is provided for rotation of the clamping device about the longitudinal axis of the pipe string. The clamping device communicates with a fluid supply via a swivel ring that encircles the drive ring of the driving mechanism. Thus Halse provides for three hundred sixty degree continuous rotation combining a spinner with a torque tong. The Halse power tong does not include a radial opening, the tong having a swivel coupling surrounding the tong for transferring pressurized fluid from an external source to the tong when the tong rotates about the axis of the pipe. Halse states that having a radial opening in a power tong complicates the design of the power tong and weakens the structure surrounding the pipe considerably, stating that as a result, the structure must be up-rated in order to accommodate the relatively large forces being transferred between the power tong and the pipe string. Halse further opines that a relatively complicated mechanical device is required to close the radial opening when the power tong is in use, and in many cases also to transfer forces between the sides of the opening. The Halse tong is not desirable for drilling operations because there is no throat opening to allow the tong to be positioned around the pipe at the operator's discretion. The pipe must always pass through the tong.